Find all School-related info fast with the new School-Specific MBA Forum

It is currently 30 Aug 2014, 08:35

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

How many integers 100>n>10 are such that, if the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 05 Sep 2007
Posts: 146
Location: New York
Followers: 1

Kudos [?]: 9 [0], given: 0

How many integers 100>n>10 are such that, if the [#permalink] New post 21 Oct 2007, 13:22
How many integers 100>n>10 are such that, if the digits of n are reversed, the resulting integer is n+9?
Director
Director
avatar
Joined: 11 Jun 2007
Posts: 932
Followers: 1

Kudos [?]: 46 [0], given: 0

GMAT Tests User
Re: Integers [#permalink] New post 21 Oct 2007, 13:41
el1981 wrote:
How many integers 100>n>10 are such that, if the digits of n are reversed, the resulting integer is n+9?


i am probably wrong but i'll take a shot at it:

i get 8 but only by logical thinking (no formulas)

12, 23, 34, 45, 56, 67, 78, 89

in order for it to be n+9, the units and tens digit has be be consecutive (since n + 10 would just be a change in the tens digit 10x)
VP
VP
avatar
Joined: 28 Mar 2006
Posts: 1390
Followers: 2

Kudos [?]: 18 [0], given: 0

GMAT Tests User
 [#permalink] New post 21 Oct 2007, 13:53
This is a 2 digit #

any two digit # is of the form 10*x+y

Now its given 10*y + x = 10*x+y + 9 (this is n+9)

So y=x+1

Hence there are 8 numbers

12
23
34
45
56
67
78
89
Manager
Manager
avatar
Joined: 30 Sep 2007
Posts: 144
Followers: 1

Kudos [?]: 5 [0], given: 0

 [#permalink] New post 21 Oct 2007, 18:32
Vikram - great formula.
  [#permalink] 21 Oct 2007, 18:32
    Similar topics Author Replies Last post
Similar
Topics:
How many integers between 100 and 150, inclusive, cannot be salr15 14 22 Jun 2007, 10:42
how many positive integers k are there such that 100k is a lan583 6 07 Nov 2006, 11:59
How many positive integers k are there such that 100k is a kidderek 2 03 Nov 2006, 21:24
How many positive integers k are there such that 100k is a sushom101 5 29 Oct 2005, 12:55
How many integers 10 < n < 100 are there when the rxs0005 3 18 Jul 2005, 14:57
Display posts from previous: Sort by

How many integers 100>n>10 are such that, if the

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.